Light emitting device, light emitting device package, method of manufacturing light emitting device and lighting system

ABSTRACT

A light emitting device according to the embodiment includes a conductive support member; a light emitting structure on the conductive support member including a first conductive semiconductor layer, a second conductive semiconductor layer, and an active layer between the first and second semiconductor layers; and a protective device on the light emitting structure.

BACKGROUND

The embodiment relates to a light emitting device, a method ofmanufacturing the same, and a light emitting device package.

A light emitting diode (LED) is a semiconductor light emitting devicethat converts current into light. The LED can generate light having highbrightness, so that the LED has been expensively used as a light sourcefor a display device, a vehicle, or a lighting device. In addition, theLED can represent a white color having superior light efficiency byemploying phosphors or combining LEDs having various colors.

In order to improve the brightness and the performance of the LED,various attempts have been performed to improve a light extractingstructure, an active layer structure, current spreading, an electrodestructure, and a structure of a light emitting diode package.

SUMMARY

The embodiment provides a light emitting device having a novelstructure, a method of manufacturing the same, and a light emittingdevice package.

The embodiment provides a light emitting device capable of improvingwithstanding voltage characteristics and a method of manufacturing thesame.

A light emitting device according to the embodiment includes aconductive support member; a second conductive semiconductor layer onthe conductive support member; an active layer on the second conductivesemiconductor layer; a first conductive semiconductor layer on theactive layer; and a protective device on the first conductivesemiconductor layer.

A method of manufacturing a light emitting device may include the stepsof forming a light emitting structure by sequentially stacking a firstconductive semiconductor layer, an active layer and a second conductivesemiconductor layer on a silicon substrate; forming a conductive supportmember on the light emitting structure; forming a body of a protectivedevice by selectively removing the silicon substrate; implanting a firstconductive dopant into the body of the protective device; forming adoping part by implanting a second conductive dopant into a lowerportion of the body; and forming an electrode on at least one of thebody and the doping part.

The embodiment can provide a light emitting device having a novelstructure, a method of manufacturing the same, and a light emittingdevice package.

The embodiment can provide a light emitting device capable of improvingwithstanding voltage characteristics and a method of manufacturing thesame.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a light emitting device according to thefirst embodiment;

FIG. 2 is a plan view of a light emitting device according to the firstembodiment;

FIG. 3 is a circuit view showing an operational principle of aprotective device of a light emitting device of FIG. 1;

FIGS. 4 to 11 are sectional views showing a method of manufacturing alight emitting device according to the first embodiment;

FIG. 12 is a sectional view of a light emitting device according to thesecond embodiment;

FIG. 13 is a sectional view of a light emitting device according to thethird embodiment;

FIG. 14 is a sectional view of a light emitting device according to thefourth embodiment;

FIG. 15 is a sectional view showing a light emitting device packageincluding a light emitting device according to the embodiments;

FIG. 16 is an exploded perspective view showing a backlight unitincluding a light emitting device or a light emitting device packageaccording to the embodiment; and

FIG. 17 is a perspective view showing a lighting unit including a lightemitting device or a light emitting device package according to theembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the description of the embodiments, it will be understood that, whena layer (or film), a region, a pattern, or a structure is referred to asbeing “on” or “under” another substrate, another layer (or film),another region, another pad, or another pattern, it can be “directly” or“indirectly” over the other substrate, layer (or film), region, pad, orpattern, or one or more intervening layers may also be present. Such aposition of the layer has been described with reference to the drawings.

The thickness and size of each layer shown in the drawings may beexaggerated, omitted or schematically drawn for the purpose ofconvenience or clarity. In addition, the size of elements does notutterly reflect an actual size.

Hereinafter, the light emitting device, a method of manufacturing thesame, a light emitting device package and a lighting system according tothe embodiment will be described with reference to accompanyingdrawings.

FIG. 1 is a sectional view showing a light emitting device 100 accordingto the first embodiment and FIG. 2 is a plan view of the light emittingdevice 100.

Referring to FIGS. 1 and 2, the light emitting device 100 includes aconductive support member 160, an adhesive layer 158 on the conductivesupport member 160, a protective member 155 on a peripheral portion of atop surface of the conductive support member 160 or the adhesive layer158, a reflective layer 157 on the adhesive layer 158, an ohmic contactlayer 156 on the protective member 155, a light emitting structure 145on the ohmic contact layer 156 and the protective member 155, a firstelectrode 170 on the light emitting structure 145, and a protectivedevice 115 on the light emitting structure 145.

The light emitting structure 145 includes at least a first conductivesemiconductor layer 130, an active layer 140 under the first conductivesemiconductor layer 130, and a second conductive semiconductor layer 150under the active layer 140. The first conductive semiconductor layer130, the active layer 140 and the second conductive semiconductor layer150 constitute a structure that generates light.

The conductive support member 160 supports the light emitting structure145 and supplies power to the light emitting device 100 together withthe first electrode 170.

The conductive support member 160 may include at least one of Ti, Cr,Ni, Al, Pt, Au, W, Cu, Mo, and a semiconductor substrate doped withimpurities.

The adhesive layer 158 may be formed on the conductive support member160. The adhesive layer 158 is a bonding layer to improve theinterfacial bonding strength between the conductive support member 160and the light emitting structure 145.

The adhesive layer 158 may include at least one of Ti, Au, Sn, Ni, Cr,Ga, In, Bi, Cu, Ag and Ta. In addition, the adhesive layer 158 may havea multi-layer structure including a plurality of heterogeneous layers.

The conductive support member 160 can be formed through the platingprocess or the deposition process. If the conductive support member 160has sufficient adhesive property, the adhesive layer 158 may be omitted.

The protective member 155 can be formed on the peripheral portion of thetop surface of the conductive support member 160 or the adhesive layer158. The protective member 155 can prevent the electric short betweenthe light emitting structure 145 and the conductive support member 160.

The protective member 155 may include a material having electricinsulating property. For instance, the protective member 155 may includeat least one selected from the group consisting of SiO₂, Si_(x)O_(y),Si₃N₄, Si_(x)N_(y), SiO_(x)N_(Y), Al₂O₃, TiO₂, ITO, AZO, and ZnO.

The reflective layer 157 can be formed on the adhesive layer 158. Thereflective layer 157 reflects the light incident from the light emittingstructure 145 to improve the light emitting efficiency of the lightemitting device 100.

The reflective layer 157 may include a material having highreflectivity. For instance, the reflective layer 157 can be formed byusing a metal or a metal alloy including at least one selected from thegroup consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and Hf.In addition, the reflective layer 157 can be prepared as a multiplelayer by using the above metal or metal alloy and a transmittiveconductive material, such as IZO, IZTO, IAZO, IGZO, IGTO, AZO, or ATO.For instance, the reflective layer may have the stack structureincluding IZO/Ni, AZO/Ag, IZO/Ag/Ni, or AZO/Ag/Ni. The reflective layer157 is provided to improve the light efficiency and may not benecessarily required. The ohmic contact layer 156 is formed on thereflective layer 157.

The ohmic contact layer 156 forms an ohmic contact such that current canflow between the reflective layer 157 and the light emitting structure145.

If the reflective layer 157 forms an ohmic contact with respect to thelight emitting structure 145, the ohmic contact layer 156 may beomitted, but the embodiment is not limited thereto.

The ohmic contact layer 156 may include at least one selected from thegroup consisting of ITO, Ni, Pt, Ir, Rh, and Ag, but the embodiment isnot limited thereto. The ohmic contact layer 156 may selectively employa transmittive conductive layer and a metal. The ohmic contact layer 156can be prepared as a single layer or a multiple layer by using at leastone selected from the group consisting of ITO (indium tin oxide), IZO(indium zinc oxide), IZTO (indium zinc tin oxide), IAZO (indium aluminumzinc oxide), IGZO (indium gallium zinc oxide), IGTO (indium gallium tinoxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO(gallium zinc oxide), IrO_(x), RuO_(x), RuO_(x)/ITO, Ni, Ag,Ni/IrO_(x)/Au, and Ni/IrO_(x)/Au/ITO.

The light emitting structure 145 may be formed on the ohmic contactlayer 156 and the protective member 155. The light emitting structure145 includes a plurality of semiconductor layers to generate the light.For instance, the light emitting structure 145 includes at least thefirst conductive semiconductor layer 130, the active layer 140 under thefirst conductive semiconductor layer 130, and the second conductivesemiconductor layer 150 under the active layer 140.

For instance, the second conductive semiconductor layer 150 may includea p type semiconductor layer. The p type semiconductor layer may includea semiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). For instance, the ptype semiconductor layer may include InAlGaN, GaN, AlGaN, InGaN, AlN, orInN doped with p type dopant, such as Mg, Zn, Ca, Sr, or Ba.

The active layer 140 is formed on the second conductive semiconductorlayer 150. The active layer 140 emits the light based on the bandgapdifference of the energy band according to intrinsic material for theactive layer 140 through the recombination of electrons (or holes)injected through the first conductive semiconductor layer 130 and holes(or electrons) injected through the second conductive semiconductorlayer 150.

The active layer 140 may have at least one of a single quantum wellstructure, a multiple quantum well (MQW) structure, a quantum dotstructure, or a quantum wire structure, but the embodiment is notlimited thereto.

The active layer 140 may include a semiconductor material having acompositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1). If the active layer 140 has the MQW structure, the activelayer 140 may include a stack structure of InGaN well/GaN barrierlayers.

A clad layer (not shown) doped with the n type or p type dopant can beformed on and/or under the active layer 140. The clad layer may includean AlGaN layer or an InAlGaN layer.

The first semiconductor layer 130 may be formed on the active layer 140.In addition, a pattern or a roughness 131 can be formed on the topsurface of the first semiconductor layer 130 to improve the lightextraction efficiency of the light emitting device 100.

An undoped semiconductor layer can be formed on the first semiconductorlayer 130, but the embodiment is not limited thereto.

The first conductive semiconductor layer may include an n typesemiconductor layer. The n type semiconductor layer may include asemiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). For instance, the firstconductive semiconductor layer may be selected from the group consistingof InAlGaN, GaN, AlGaN, InGaN, AlN, and InN, and may be doped with ntype dopant such as Si, Ge, or Sn.

In contrast, the first conductive semiconductor layer 130 may include ap type semiconductor layer, and the second conductive semiconductorlayer 150 may include an n type semiconductor layer. In addition, athird conductive semiconductor layer including an n type semiconductorlayer or a p type semiconductor layer may be formed on the firstconductive semiconductor layer 130. Accordingly, the light emittingdevice 100 may include at least one of NP, PN, NPN, and PNP junctionstructures. In addition, the doping concentration of impurities in thefirst and second conductive semiconductor layers may be uniform orirregular. In other words, the light emitting structure 145 may havevarious configurations, and the embodiment is not limited thereto.

A current blocking layer (not shown) may be formed between the ohmiccontact layer 156 and the second conductive semiconductor layer 150. Atop surface of the current blocking layer makes contact with the secondconductive semiconductor layer 150 and a bottom surface and lateralsides of the current blocking layer make contact with the ohmic contactlayer 156.

At least a part of the current blocking layer may overlap with the firstelectrode 170. Therefore, the current blocking layer can restrict thecurrent from flowing through the shortest path between the firstelectrode 170 and the conductive support member 160, so that the lightemitting efficiency of the light emitting device 100 can be improved.

The current blocking layer may include a material having electricconductivity lower than that of the reflective layer 157 or the ohmiccontact layer 156, a material forming a schottky contact with respect tothe second conductive semiconductor layer 150, or an electric insulatingmaterial.

For instance, the current blocking layer may include may include atleast one of ZnO, SiO₂, SiON, Si₃N₄, Al₂O₃, TiO₂, Ti, Al and Cr.

The first electrode 170 and the protective device 115 may be formed onthe first conductive semiconductor layer 130.

The first electrode 170 and the conductive support member 160 supplypower to the light emitting device 100. For instance, the firstelectrode 170 includes at least one of Al, Ti, Cr, Ni, Cu, and Au. Thefirst electrode 170 can be prepared as a multi-layer structure includinga plurality of layers formed by using heterogeneous materials.

The protective device 115 is formed on the first conductivesemiconductor layer 130. Preferably, the protective device 115 is formedon an outer peripheral portion of the top surface of the firstconductive semiconductor layer 130 to minimize absorption of the lightemitted from the light emitting structure 145.

The protective device 115 can protect the light emitting structure 145from the surge or the electrostatic discharge occurs due to the overvoltage, over current or reverse voltage. That is, when the overvoltage, over current or reverse voltage is generated, the current flowsto the protective device 115, other than the light emitting structure,so that the light emitting structure 145 can be prevented from beingdamaged, thereby improving the withstanding voltage characteristics ofthe light emitting device 100.

The protective device 115 can be formed on the first conductivesemiconductor layer 130 of the light emitting structure 145. Forinstance, the protective device 115 can be formed in a micro-size bydoping silicon in the semiconductor manufacturing process, so theprotective device 115 can achieve the original purpose thereof withoutdegrading the light emitting efficiency of the light emitting device100.

The protective device 115 includes a conductive member 110 a made from asilicon material and doped with p type dopant, a doping part 112 formedon the conductive member 110 a and doped with n type dopant, a thirdelectrode 114 on the conductive member 110 a, and the second electrode116 on the doping part 112.

The conductive member 110 a includes a silicon material and can beformed by selectively removing a silicon substrate through an etchingprocess. In detail, the silicon substrate, which is used to grow thelight emitting structure 145, is selectively removed to form theconductive member 110 a of the protective device 115, so that themanufacturing process can be simply performed with high efficiency.

The conductive member 110 a is doped with p type dopant, so that theconductive member 110 a constitutes a p type semiconductor. The p typedopant may include at least one of Mg, Be and B.

The doping part 112 can be formed on the conductive member 110 a byimplanting n type dopant into the top surface of the conductive member110 a. The n type dopant may include at least one of N, P, As and Sb.

If the first conductive semiconductor layer 130 is a p typesemiconductor layer and the second conductive semiconductor layer 150 isan n type semiconductor layer, the n type dopant is implanted into theconductive member and the p type dopant is implanted into the dopingpart 112.

The third electrode 114 is formed on the conductive member 110 a and thesecond electrode 116 is formed on the doping part 112. The second andthird electrodes 116 and 114 are provided with wires electricallyconnected to external electrodes.

The first and third electrodes 170 and 114 can be electrically connectedto the same external electrode, and the conductive support member 160and the second electrode 116 are electrically connected to the sameexternal electrode.

FIG. 3 is a circuit view showing the operational principle of theprotective device 115.

Referring to FIG. 3, the protective device 115 is connected to the lightemitting structure 145 in parallel to serve as diodes that allow forwardcurrents to flow in the opposite directions. In particular, theprotective device 115 may serve as a Zener diode having breakdownvoltage at least higher than operational voltage of the light emittingstructure 145.

If a first current I1 is applied to the light emitting device 100, thefirst current I1 is a reverse current for the light emitting structure145 and a forward current for the protective device 115, so the currentflows only through the protective device 115.

In contrast, if a second current I2 is applied to the light emittingdevice 100, the second current I2 is a forward current for the lightemitting structure 145 and a reverse current for the protective device115, so the current flows only through the protective device 115, sothat the light emitting device 100 emits the light.

Meanwhile, if the second current I2 is an over current subject to theover voltage higher than the breakdown voltage of the protective device115, the protective device 115 is enabled due to the tunneling effect sothat the current flows through protective device 115. That is, the overcurrent flows through the protective device 115, other than the lightemitting structure 145, so that the light emitting structure 145 can beprevented from being damaged.

The breakdown voltage of the protective device 115 may be higher thanthe operational voltage of the light emitting structure 145. Forinstance, the breakdown voltage of the protective device 115 may be inthe range of 3V to 100V, but the embodiment is not limited thereto. Thebreakdown voltage of the protective device 115 may be determined byadjusting the size and the doping concentration of the conductive member110 a and the doping part 112.

As described above, the protective device 115 can be formed on the topsurface of the light emitting structure 145 through the simple andefficient process, so that the light emitting device 100 can beprotected from the over current and the reverse current, therebyimproving the reliability of the light emitting device 100.

Hereinafter, the method of manufacturing the light emitting device 100according to the first embodiment will be described in detail.

FIGS. 4 to 11 are sectional views showing the method of manufacturingthe light emitting device 100 according to the first embodiment.

Referring to FIG. 4, the light emitting structure 145 is formed on thesilicon substrate 110. The light emitting structure 145 can be formed bysequentially depositing the first conductive semiconductor layer 130,the active layer 140, and the second conductive semiconductor layer 150on the silicon substrate 110.

The silicon substrate 110 may include silicon. The silicon isinexpensive and easily processed as compared with a sapphire substrate.

The light emitting structure 145 can be formed on the silicon substrate110 through MOCVD (metal organic chemical vapor deposition), CVD(chemical vapor deposition), PECVD (plasma-enhanced chemical vapordeposition), MBE (molecular beam epitaxy), or HVPE (hydride vapor phaseepitaxy), but the embodiment is not limited thereto.

A buffer layer (not shown) can be formed between the first conductivesemiconductor layer 130 and the silicon substrate 110 to attenuate thelattice mismatch and difference of the thermal explanation coefficientbetween the first conductive semiconductor layer 130 and the siliconsubstrate 110. For instance, the buffer layer can be prepared as asingle layer or a multi-layer by using a semiconductor material havingthe compositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1).

Referring to FIG. 5, the protective member 155 is formed on theperipheral portion of the light emitting structure 145. The protectivemember 155 may include a material having electric insulating property.For instance, the protective member 155 may include at least oneselected from the group consisting of SiO₂, Si_(x)O_(y), Si₃N₄,Si_(x)N_(y), SiO_(x)N_(y), Al₂O₃, TiO₂, ITO, AZO, AND ZnO. Theprotective member 155 may be formed through the deposition process, suchas sputtering or PECVD, but the embodiment is not limited thereto.

Referring to FIG. 6, the ohmic contact layer 156 is formed on the lightemitting structure 145 and the reflective layer 157 is formed on theohmic contact layer 156. The ohmic contact layer 156 and the reflectivelayer 157 can be formed through the deposition process, such assputtering, PECVD, or E-beam evaporation, but the embodiment is notlimited thereto.

The ohmic contact layer 156 may include at least one of ITO, Ni, Pt, Ir,Rh, and Ag. In addition, the reflective layer 157 may include a metal oran alloy including at least one of Ag, Al, Pt, Pd, and Cu.

Referring to FIG. 7, the adhesive layer 158 is formed on the reflectivelayer 157 and the protective member 155, and the conductive supportmember 160 is formed on the adhesive layer 158.

The adhesive layer 158 may improve the interfacial adhesive strengthbetween the conductive support member 160 and the light emittingstructure 145. For instance, the adhesive layer 158 may include at leastone selected from the group consisting of Ti, Au, Sn, Ni, Cr, Ga, In,Bi, Cu, Ag and Ta.

The conductive support member 160 is prepared as a sheet and bonded ontothe top surface of the adhesive layer 158. Otherwise, the conductivesupport member 160 can be formed through the plating process or thedeposition process. In this case, the adhesive layer 158 may be omitted.

The conductive support member 160 may include at least one of Ti, Cr,Ni, Al, Pt, Au, W, Cu, Mo, and a semiconductor substrate doped withimpurities.

Referring to FIG. 8, the conductive member 110 a of the protectivedevice 115 is formed by selectively removing the silicon substrate 110.Preferably, the conductive member 110 a is formed on the outerperipheral region of the bottom surface of the light emitting structure145, but the embodiment is not limited thereto.

In detail, the silicon substrate 110 is selectively etched to form theconductive member 110 a of the protective device 115. Preferably, asshown in FIG. 8, the conductive member 110 a may have a polygonal columnshape, but the embodiment may not limit the shape and the manufacturingprocess for the conductive member 110 a. After that, the p type dopantis implanted into the conductive member 110 a, so that the p typesemiconductor layer is formed.

Since the silicon substrate 110 can be easily removed through theetching process, the LLO (laser lift off) process, which may reduce theproduct yield of the light emitting device, can be omitted, so that thereliability of the manufacturing process for the light emitting device100 can be improved.

Meanwhile, the sapphire substrate can be employed as a base substrate ofthe light emitting structure 145 instead of the silicon substrate. Inthis case, the sapphire substrate is selectively removed through the LLOprocess and the conductive member 110 a is formed on the light emittingstructure 145 through the deposition process, but the embodiment is notlimited thereto.

Referring to FIG. 9, the n type dopant is selectively implanted into thelower portion of the conductive member 110 a to form the doping part112. The doping part 112 is formed at a part of the lower portion of theconductive member 110 a.

In order to form the doping part 112 in a desired position, the maskpattern is formed in the conductive member 110 a and the n type dopantis implanted along the mask pattern through the ion implantation or thethermal diffusion, but the embodiment is not limited thereto.

Referring to FIG. 10, the isolation etching is performed with respect tothe light emitting structure 145 and the pattern or the roughness 131 isformed on the bottom surface of the light emitting structure 145, thatis, on the bottom surface of the first conductive semiconductor layer130 to improve the light extraction efficiency.

The light emitting device chips can be divided into individual chipunits through the isolation etching. In addition, the light extractionefficiency can be improved by the pattern or the roughness 131.

A passivation layer (not shown) can be formed on at least one lateralside of the light emitting structure 145 to protect the light emittingstructure 145. For instance, the passivation layer includes SiO₂,SiO_(x), SiO_(x)N_(y), Si₃N₄, or Al₂O₃, but the embodiment is notlimited thereto.

Referring to FIG. 11, the first electrode 170 is formed on the bottomsurface of the light emitting structure 145, the third electrode 114 isformed on the bottom surface of the conductive member 110 a, and thesecond electrode 116 is formed on the bottom surface of the doping part112, thereby providing the light emitting device 100 including theprotective device 115 according to the first embodiment.

At this time, the first and third electrodes 170 and 114 can beelectrically connected to the same external electrode, and theconductive support member 160 and the second electrode 116 areelectrically connected to the same external electrode.

Hereinafter, a light emitting device 100B and a method of manufacturingthe same according to the second embodiment will be described in detail.

FIG. 12 is a sectional view of a light emitting device 100E according tothe second embodiment. The light emitting device 100B according to thesecond embodiment is similar to the light emitting device 100 accordingto the first embodiment except for the electrode of the protectivedevice and the operational principle thereof.

Referring to FIG. 12, the light emitting device 100B according to thesecond embodiment includes a conductive support member 160, an adhesivelayer 158 on the conductive support member 160, a protective member 155on the conductive support member 160 or on an outer peripheral region ofa top surface of the adhesive layer 158, a reflective layer 157 on theadhesive layer 158, an ohmic contact layer 156 on the reflective layer157, a light emitting structure 145 on the protective member 155 and theohmic contact layer 156, a first electrode 170 on the light emittingstructure 145, and a protective device 115 b on the light emittingstructure 145.

The light emitting structure 145 includes at least a first conductivesemiconductor layer 130, an active layer 140 under the first conductivesemiconductor layer 130, and a second conductive semiconductor layer 150under the active layer 140. The first conductive semiconductor layer130, the active layer 140 and the second conductive semiconductor layer150 constitute a structure that generates light.

The following description will be made on the assumption that the firstconductive semiconductor layer 130 includes an n type semiconductorlayer and the second conductive semiconductor layer 150 includes a ptype semiconductor layer, but the embodiment is not limited thereto.

The protective device 115 b includes a conductive member 110 a made froma silicon material and doped with n type dopant, a doping part 112formed on the conductive member 110 a and doped with p type dopant, anda second electrode 116 on the doping part 112. The second electrode 116and the conductive support member 160 are connected to the same externalpower source.

If the forward current flows through the light emitting structure 145,the current may not flow through the protective device 115 b so that theprotective device 115 b is not operated.

If the reverse current is applied to the light emitting structure 145,the current flows through the protective device 115 b and the firstconductive semiconductor layer 130, other than the light emittingstructure 145, so that the active layer of the light emitting structure145 can be prevented from being damaged.

In addition, if the excessive forward current higher than the breakdownvoltage of the protective device 115 b is applied to the light emittingstructure, the protective device 115 b is enabled, so that the currentflows through the protective device 115 b and the first conductivesemiconductor layer 130, other than the light emitting structure 145, sothat the active layer of the light emitting structure 145 can beprevented from being damaged.

Hereinafter, a light emitting device 100C and a method of manufacturingthe same according to the third embodiment will be described in detail.

FIG. 13 is a sectional view of a light emitting device 100C according tothe third embodiment. The light emitting device 100C according to thethird embodiment is similar to the light emitting device 100 accordingto the first embodiment except for the first electrode, and the dopingand operation principle of the protective device.

Referring to FIG. 13, the light emitting device 100C according to thethird embodiment includes a conductive support member 160, an adhesivelayer 158 on the conductive support member 160, a protective member 155on the conductive support member 160 or on an outer peripheral region ofa top surface of the adhesive layer 158, a reflective layer 157 on theadhesive layer 158, an ohmic contact layer 156 on the reflective layer157, a light emitting structure 145 on the protective member 155 and theohmic contact layer 156, a protective device 115 c on the light emittingstructure 145 and a second and third electrodes 116 and 114 on theprotective device 115 c.

The light emitting structure 145 includes at least a first conductivesemiconductor layer 130, an active layer 140 under the first conductivesemiconductor layer 130, and a second conductive semiconductor layer 150under the active layer 140. The first conductive semiconductor layer130, the active layer 140 and the second conductive semiconductor layer150 constitute a structure that generates light. The followingdescription will be made on the assumption that the first conductivesemiconductor layer 130 includes an n type semiconductor layer and thesecond conductive semiconductor layer 150 includes a p typesemiconductor layer, but the embodiment is not limited thereto.

The protective device 115 c includes a conductive member 110 a made froma silicon material and doped with n type dopant, a doping part 112formed on the conductive member 110 a and doped with p type dopant, thesecond electrode 116 on the doping part 112 and the third electrode 114on the conductive member 110 a.

In normal cases, that is, when the forward current is applied to thelight emitting device 100C, the third electrode 114 and the conductivesupport member 160 supply power to the light emitting structure 145.This is because the conductive member 110 a of the protective device 115c has polarity (n type) identical to that of the first conductivesemiconductor layer 130.

If the reverse current is applied to the light emitting device 100C, thereverse current may not flow due to the rectifying function of theprotective device 115 c. However, if excessive reverse current isapplied, the protective device 115 c is enabled so that the reversecurrent flows through the protective device 115 c, thereby protectingthe light emitting structure 145 of the light emitting device 100C.

FIG. 14 is a sectional view of a light emitting device 100D according tothe fourth embodiment. According to the light emitting device 100D ofthe fourth embodiment, a passivation layer 180 is formed on a lateralside of the light emitting structure 145 to protect the light emittingstructure 145 from the external impact.

In the region where the protective device 115 d is formed, the adhesivelayer 158 is partially exposed through the protective member 155.

In detail, the protective member 155 formed in the region where theprotective device 115 d is formed may have a width narrower than theprotective member 155 formed in the region where the protective device115 d is not formed, so that the adhesive layer 158 is partiallyexposed. In addition, the second electrode 116 is connected to theexposed part of the adhesive layer 158.

The second electrode 116 is formed on the passivation layer 180 adjacentto the protective device 115 d and electrically connected to theadhesive layer 158. In detail, one end of the second electrode 116 makescontact with the doping part 112 and the other end of the secondelectrode 116 is connected to the adhesive layer 158. That is, thesecond electrode 116 is connected to the adhesive layer 158 andelectrically connected to the conductive support member 160.

Referring to FIG. 14, the light emitting device 100D according to thefourth embodiment includes a conductive support member 160, an adhesivelayer 158 on the conductive support member 160, a protective member 155on the conductive support member 160 or on an outer peripheral region ofa top surface of the adhesive layer 158, a reflective layer 157 on theadhesive layer 158, an ohmic contact layer 156 on the reflective layer157, a light emitting structure 145 on the protective member 155 and theohmic contact layer 156, a protective device 115 d on the light emittingstructure 145, and second and third electrodes 116 and 114 on theprotective device 115 d.

The light emitting structure 145 includes at least a first conductivesemiconductor layer 130, an active layer 140 under the first conductivesemiconductor layer 130, and a second conductive semiconductor layer 150under the active layer 140. The first conductive semiconductor layer130, the active layer 140 and the second conductive semiconductor layer150 constitute a structure that generates light. The followingdescription will be made on the assumption that the first conductivesemiconductor layer 130 includes an n type semiconductor layer and thesecond conductive semiconductor layer 150 includes a p typesemiconductor layer, but the embodiment is not limited thereto.

The protective device 115 d includes a conductive member 110 a made froma silicon material and doped with n type dopant, a doping part 112formed on the conductive member 110 a and doped with p type dopant, thesecond electrode 116 on the doping part 112 and the third electrode 114on the conductive member 110 a.

In normal cases, that is, when the forward current is applied to thelight emitting device 100D, the third electrode 114 and the conductivesupport member 160 supply power to the light emitting structure 145.This is because the conductive member 110 a of the protective device 115d has polarity (n type) identical to that of the first conductivesemiconductor layer 130.

If the reverse current is applied to the light emitting device 100D, thereverse current may not flow due to the rectifying function of theprotective device 115 d. However, if excessive reverse current isapplied, the protective device 115 d is enabled so that the reversecurrent flows through the protective device 115 d, thereby protectingthe light emitting structure 145 of the light emitting device 100D.

FIG. 15 is a sectional view showing a light emitting device packageincluding the light emitting device according to the embodiments.

Referring to FIG. 15, the light emitting device package includes apackage body 20, first and second electrode layers 31 and 32 formed onthe package body 20, the light emitting device 100 provided on thepackage body 20 and electrically connected to the first and secondelectrode layers 31 and 32 and a molding member 40 that surrounds thelight emitting device 100.

The package body 20 may include silicon, synthetic resin or metallicmaterial. An inclined inner wall may be formed around the light emittingdevice.

The first and second electrode layers 31 and 32 are electricallyisolated from each other to supply power to the light emitting device100. In addition, the first and second lead electrodes 31 and 32 reflectthe light emitted from the light emitting device 100 to improve thelight efficiency and dissipate heat generated from the light emittingdevice 100 to the outside.

The light emitting device 100 is installed on the package body 20 andelectrically connected to the first and second electrode layers 31 and32. In detail, the light emitting device 100 is installed on one of thefirst and second electrode layers 31 and 32 and connected to the otherof the first and second electrode layers 31 and 32 through a wire. Theprotective device of the light emitting device 100 is connected to thefirst and second electrode layers 31 and 32 through a wire. However, theembodiment does not limit the electrode connection structure of thelight emitting device 100.

The molding member 40 surrounds the light emitting device 100 to protectthe light emitting device 100. In addition, the molding member 40 mayinclude luminescence materials to change the wavelength of the lightemitted from the light emitting device 100.

FIG. 16 is an exploded perspective view showing a backlight unit 1100including the light emitting device or the light emitting device packageaccording to the embodiment. The backlight unit 1100 shown in FIG. 16 isan example of a lighting system, but the embodiment is not limitedthereto.

Referring to FIG. 16, the backlight unit 1100 includes a bottom frame1140, a light guide member 1120 installed in the bottom frame 1140, anda light emitting module 1110 installed at one side or on the bottomsurface of the light guide member 1120. In addition, a reflective sheet1130 is disposed below the light guide member 1120.

The bottom frame 1140 has a box shape having an open top surface toreceive the light guide member 1120, the light emitting module 1110 andthe reflective sheet 1130 therein. In addition, the bottom frame 1140may include a metallic material or a resin material, but the embodimentis not limited thereto.

The light emitting module 1110 may include a substrate and a pluralityof light emitting device packages installed on the substrate accordingto the embodiments. The light emitting device packages 600 provide thelight to the light guide member 1120.

As shown in FIG. 16, the light emitting module 1110 is installed on atleast one inner side of the bottom frame 1140 to provide the light to atleast one side of the light guide member 1120.

In addition, the light emitting module 1110 can be provided below thebottom frame 1140 to provide the light toward the bottom surface of thelight guide member 1120. Such an arrangement can be variously changedaccording to the design of the backlight unit 1100, but the embodimentis not limited thereto.

The light guide member 1120 is installed in the bottom frame 1140. Thelight guide member 1120 converts the light emitted from the lightemitting module 1110 into the surface light to guide the surface lighttoward a display panel (not shown).

The light guide member 1120 may include a liquid guide plate. The liquidguide plate can be manufactured by using acryl-based resin, such as PMMA(polymethyl methacrylate), PET (polyethylene terephthalate), PC(polycarbonate), COC or PEN (polyethylene naphthalate) resin.

An optical sheet 1150 may be provided over the light guide member 1120.

The optical sheet 1150 may include at least one of a diffusion sheet, alight collection sheet, a brightness enhancement sheet, and afluorescent sheet. For instance, the optical sheet 1150 has a stackstructure of the diffusion sheet, the light collection sheet, thebrightness enhancement sheet, and the fluorescent sheet. In this case,the diffusion sheet uniformly diffuses the light emitted from the lightemitting module 1110 such that the diffused light can be collected onthe display panel (not shown) by the light collection sheet. The lightoutput from the light collection sheet is randomly polarized and thebrightness enhancement sheet increases the degree of polarization of thelight output from the light collection sheet. The light collection sheetmay include a horizontal and/or vertical prism sheet. In addition, thebrightness enhancement sheet may include a dual brightness enhancementfilm and the fluorescent sheet may include a transmittive plate or atransmittive film including luminescence materials.

The reflective sheet 1130 can be disposed below the light guide member1120. The reflective sheet 1130 reflects the light, which is emittedthrough the bottom surface of the light guide member 1120, toward thelight exit surface of the light guide member 1120.

The reflective sheet 1130 may include resin material having highreflectivity, such as PET, PC or PVC resin, but the embodiment is notlimited thereto.

FIG. 17 is a perspective view showing a lighting unit 1200 including thelight emitting device or the light emitting device package according tothe embodiment. The lighting unit 1200 shown in FIG. 17 is an example ofa lighting system and the embodiment is not limited thereto.

Referring to FIG. 17, the lighting unit 1200 includes a case body 1210,a light emitting module 1230 installed in the case body 1210, and aconnection terminal 1220 installed in the case body 1210 to receivepower from an external power source.

Preferably, the case body 1210 includes material having superior heatdissipation property. For instance, the case body 1210 includes ametallic material or a resin material.

The light emitting module 1230 may include a substrate 300 and at leastone light emitting device package 200 installed on the substrate 300.

The substrate 300 includes an insulating member printed with a circuitpattern. For instance, the substrate 300 includes a PCB (printed circuitboard), an MC (metal core) PCB, a flexible PCB, or a ceramic PCB.

In addition, the substrate 300 may include a material that effectivelyreflects the light. The surface of the substrate 300 can be coated witha color, such as a white color or a silver color, to effectively reflectthe light.

At least one light emitting device package 200 according to theembodiment can be installed on the substrate 300. Each light emittingdevice package 200 may include at least one LED (light emitting diode).The LED may include a colored LED that emits the light having the colorof red, green, blue or white and a UV (ultraviolet) LED that emits UVlight.

The LEDs of the light emitting module 1230 can be variously combined toprovide various colors and brightness. For instance, the white LED, thered LED and the green LED can be combined to achieve the high colorrendering index (CRI). In addition, a fluorescent sheet can be providedin the path of the light emitted from the light emitting module 1230 tochange the wavelength of the light emitted from the light emittingmodule 1230. For instance, if the light emitted from the light emittingmodule 1230 has a wavelength band of blue light, the fluorescent sheetmay include yellow luminescence materials. In this case, the lightemitted from the light emitting module 1230 passes through thefluorescent sheet so that the light is viewed as white light.

The connection terminal 1220 is electrically connected to the lightemitting module 1230 to supply power to the light emitting module 1230.Referring to FIG. 17, the connection terminal 1220 has a shape of asocket screw-coupled with the external power source, but the embodimentis not limited thereto. For instance, the connection terminal 1220 canbe prepared in the form of a pin inserted into the external power sourceor connected to the external power source through a wire.

According to the lighting system as described above, at least one of thelight guide member, the diffusion sheet, the light collection sheet, thebrightness enhancement sheet and the fluorescent sheet is provided inthe path of the light emitted from the light emitting module, so thatthe desired optical effect can be achieved.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A light emitting device comprising: a lightemitting structure including: a first conductive semiconductor layer; asecond conductive semiconductor layer; and an active layer between thefirst and second semiconductor layers; a support electrode layer on abottom surface of the light emitting structure; a first electrode on afirst top surface area of the light emitting structure; a protectivedevice on a second top surface of the light emitting structure; and aprotective member at an outer peripheral portion of a top surface of thesupport electrode layer, wherein the second conductive semiconductorlayer is disposed on the support electrode layer and the protectivemember, wherein the protective device includes a semiconductor material,and wherein the protective device vertically overlaps with at least oneportion of the protective member.
 2. The light emitting device of claim1, wherein the protective device includes: a body; a doping partdisposed at an upper portion of the body; and a second electrode on thedoping part, and wherein a bottom side of the body is directly disposedon the upper surface of the first conductive semiconductor layer.
 3. Thelight emitting device of claim 2, wherein at least one top surface areaof the protective member is exposed.
 4. The light emitting device ofclaim 3, wherein the second conductive semiconductor layer is disposedon the support electrode layer and the protective member.
 5. The lightemitting device of claim 1, wherein a bottom surface of the protectivedevice is higher than a top surface of the first electrode.
 6. The lightemitting device of claim 1, wherein the protective device is disposed ononly an upper surface of the first conductive semiconductor layer. 7.The light emitting device of claim 1, wherein a lateral width of theprotective device is smaller than a lateral width of the light emittingstructure.
 8. The light emitting device of claim 1, wherein theprotective device includes a body including first conductive dopants, adoping part disposed at an upper portion of the body and includingsecond conductive dopants, and a second electrode on the doping part. 9.The light emitting device of claim 8, wherein a bottom side of the bodyis directly disposed on the upper surface of the first conductivesemiconductor layer.
 10. The light emitting device of claim 8, whereinthe first conductive dopants of the body are an opposite conductive typethan the first conductive semiconductor layer.
 11. The light emittingdevice of claim 8, wherein the first conductive semiconductor layerincludes an N type semiconductor layer, the second conductivesemiconductor layer includes a P type semiconductor layer, the firstconductive dopants are P type dopants, and the second conductive dopantsare N type dopants.
 12. The light emitting device of claim 1, furthercomprising at least one of a reflective layer and an ohmic contact layerbetween the support electrode layer, and the second conductivesemiconductor layer.
 13. A light emitting device comprising: a lightemitting structure including a first conductive semiconductor layer, asecond conductive semiconductor layer and an active layer between thefirst and second semiconductor layers; a support electrode layer on abottom surface of the light emitting structure; a first electrode on afirst top surface area of the light emitting structure; a protectivedevice on a second top surface of the light emitting structure; and aprotective member at an outer peripheral portion of a top surface of thesupport electrode layer, wherein the protective device verticallyoverlaps with at least one portion of the protective member.
 14. Thelight emitting device of claim 13, wherein the protective deviceincludes: a body; a doping part disposed at an upper portion of thebody; and a second electrode on the doping part, and wherein a bottomside of the body is directly disposed on the upper surface of the firstconductive semiconductor layer.
 15. The light emitting device of claim13, wherein a bottom surface of the protective device is higher than atop surface of the first electrode.
 16. The light emitting device ofclaim 13, wherein the protective device includes a body including firstconductive dopants, a doping part disposed at an upper portion of thebody and including second conductive dopants, and a second electrode onthe doping part.
 17. The light emitting device of claim 16, wherein thefirst conductive dopants of the body are an opposite conductive typethan the first conductive semiconductor layer.
 18. A light emittingdevice comprising: a light emitting structure including a firstconductive semiconductor layer, a second conductive semiconductor layerand an active layer between the first and second semiconductor layers; asupport electrode layer on a bottom surface of the light emittingstructure; a protective device on a top surface of the light emittingstructure; and a protective member at an outer peripheral portion of atop surface of the support electrode layer, wherein the protectivedevice vertically overlaps with at least one portion of the protectivemember, wherein the protective device includes a body including firstconductive dopants, a doping part disposed at an upper portion of thebody and including second conductive dopants, and a second electrode onthe doping part, and wherein the first conductive dopants of the bodyare an opposite conductive type than the first conductive semiconductorlayer.
 19. The light emitting device of claim 18, wherein a bottom sideof the body is directly disposed on the upper surface of the firstconductive semiconductor layer.
 20. The light emitting device of claim18, wherein a bottom surface of the protective device is higher than atop surface of the first electrode.